Portable hair dryers



March 7, 1967 N. L AING 3,308,268

PORTABLE HAIR DRYERS Filed April l2, 1965 2 Sheets-Sheet 1 A 77M N575 March 7, 1967 N. LAING 3,308,268

PORTABLE HAIR DRYERS Filed April l2, 1965 2 Sheets-Sheet 2 United States Patent iiiice 3,388,258 Patented Mar. 7, 1967 3,308,268 Y PORTABLE HAIR DRYERS Nikolaus Laing, Hofener Weg. 35, Aldingen, near Stuttgart, Germany Filed Apr. 12, 1965, Ser. No. 447,264 Claims priority, application Germany, Apr. 15, 1959, L 32,977, L 23,717; Apr. 17, 1959, L 33,210 9 Claims. (Cl. 219-370) said rear wall extending the width of the casing between said end walls; a motor located in said casing adjacent to and centrally of the rear wall and having a driving shaft; a pair of cylindrical bladed rotors mounted on opposite ends of the driving shaft between the motor and the adjacent end wall; wall means defining with the casing bottom wall an outlet duct leading from the rotors to the outlet; electric heating means in said outlet duct; the rotors being effective on rotation by said motor to induce a flow of air into the inlets, through the respective rotors, through the outlet duct past the heating means and out of the outlet,

`The rotors may, according to the invention each cooperate with adjacent surfaces to act as cross flow fans, that is to induce the flow of air to pass twice through the path of the rotating blades, substantially in planes extending transverse to the axis of the rotors. In this case the wall means within the casing is a dividing wall extending between the end walls to define therewith and with the top wall an inlet region with which the inlets communicating, the rotors taking air from this inlet region.

Alternatively the rotors and cooperating surfaces may act as centrifugal rotors: in this case the ends of the rotors facing the end walls are open and the inlets are formed in alignment with these open ends. The Wall means which with the bottom wall defines the outlet duct is in this case part of the top wall, and the rear wall forms part of a volute or scoll around the rotors.

In either case, whether the rotors act in cross-flow or centrifugal manner, the outlet duct brings together over the heater means, the ilow from the two rotors and is preferably convergent for this purpose; conveniently the end walls converge toward the outlet.

The size of the appliance may be made quite small, particularly if a commutator motor is used, as is preferred, such motor having a relatively high speed. The appliance may indeed be made so small as to be capable of being held in the hand without the conventional handle.

The terms top bottom rear and end are used herein for convenience of `description only and do not of course imply any particular or necessary orientation of the hair dryer in space or with respect to the user.

These and further features of the invention will be illustrated by the following description of two preferred embodiments of the invention made with reference to the accompanying somewhat diagrammatic drawings in which:

FIGURE 1 is a perspective view from the top and front of a first form of hair dryer according to the invention where the rotors operate in cross-flow manner;

FIGURE 2 is a combined plan view and sectional plan of the FIGURE 1 hair dryer, the section being taken along the lines Il-II of FIGURE 3;

FIGURE 3 is a combined end elevation and transverse section of the FIGURE 1 hair dryer.

FIGURE 4 is a combined view somewhat` similar to FIGURE 2 of a second form of hair dryer according to the invention using rotors operating in centrifugal manner;

FIGURE 5 is a transverse sectional view illustrating the FIGURE 4 hair dryer-the section lines are shown respectively at V-V and VI-VI in FIGURE 4; and

FIGURE 6 is an illustration of a preferred form of an electrical circuit used in a hair dryer constructed according to the invention.

Referring to the drawings, the hair dryer shown in FIGURES 1 to 3 comprises generally slab-shaped housing designated generally 1 which is rectangular in plan and has the form of a slightly bulged-up rectangle with rounded ends. The housing 1 has a top wall 2, a bottom wall 3 and end walls 4, 5 and is formed in two interlocking unitary moulded parts, an upper and a lower part, indicated generally at 6, 7 respectively. The top and bottom housing walls 2, 3 curve round to merge with one another and together define an approximately semi-cylindrical rear wall portion 8 over the length of one short side of the rectangle. Within the housing and adjacent the middle of this wall portion is located a small electric motor of the low voltage commutator type indicated simply as a box and designated 9. The shaft 10 of the motor 9 extends parallel to the wall portion 8 and carries in overhung fashion two similar rotor portions 11, 12 one extending between the motor and one end wall 4 and the other between the motor and the other end wall 5. Each rotor portion 11, 12 comprises a series of curved blades 13 extending from an end support disc 14 mounted on the shaft 10, the blades running parallel to the shaft axis and being arranged in a ring thereabout,

to define an unobstructed interior space. The blades 13 are concave facing in the direction of rotation indicated by the arrow 15 with their outer edges leading.

The lower housing part 7 includes a partition wall 16 extending between the end walls 4, S and from lines 17 adjacent the rotors to the opposite side of the housing 1 where, with the bottom wall 3 and end walls, 4, 5 it` deiines a slot-like outlet 18. The partition wall .16 and bottom wall 3 together define a fiat outlet duct 19 leading from the rotors to the outlet 18, which duct is convergent due to the slightconvergence of the wall 16 with the bottom wall as it approaches the outlet. The partition wall 16 also deiines with the top housing wall 2 an entry region 21; air enters the region 21 through a series of slits 21a formed in the end walls 4, 5 and in a front wall 2a above the outlet 18, and ilows towards the rotor portions 11,A 12. A guide wall 22 extends upwards from the partition wall 16 over the whole length of each rotor portions 11,y 12. Each guide wall 22 forms with the corresponding rotor a gap 23 converging with the rotor portion in the direction of rotation as shown by arrow 15. Each guide wall 22 is rounded intov the partition wall at the corresponding line 17 and makes an an-gle of about therewith. Both the wall portion 8 and the guide walls 22 are well spaced from the rotor portions 11, 12 at their lines of nearest approach.'

On rotation of the rotor portions 1-1, 12 by the motor 9 a vortex of approximately Rankine type form-s in each rotor portion. The core of the vortex is indicated at V and is a whirling body of air with no translational movementas a whole. Flow through each rotor by reason of the vortex takes place approximately along the lines indicated at F, MF, the line MF showing the path of faster stream tubes: in passing through the rotor the air is turned through an angle approaching 180. The air iiow leaves through the outlet 18.

The housing parts 6, 7 are rigidified by ribs formed respectively on the underside of the top wall 2 and upper side fo the partition wall 16. A series of vanes 27 extend between the partition wall 16 and the bottom housing wall 3, at the outlet 18; these vanes cause little obstruction to air flow but rigidity the lower housing part 7 and prevent a users lingers from getting into the outlet .18.

An electric heater 28 extends across the outlet duct 19, and` comprises a resistor wire 29 wound about a platelike insulating support 30 mounted between the side walls 4, 5. An overload cut-out, not shown, is provided to open-circuit the heater .28 in the event of overheating. The resistor 29 or a part thereof can be made to form a voltage dropper for the motor 9.

A depression 36 is formed in the upper casing wall 2, so that the casing 1 can Vreadily be grasped in the users hand, with fingers and thu-mb on top and bottom walls, and the palm of the hand embracing the rear wall 8. In this position of the hand the inlet slits 21a cannot be blocked.

The hair dryer illustrated in FIGURES 4 and 5 is similar in many respects to that previously described and the same reference numerals will be used for similar parts, which will not need further description.

The ymain diiierences between the two hair dryers derive from the fact that that of FIGURES 4 and 5 has its rotors 49 operating as centrifugal rotors, with open ends 5t) facing aligned inlets 51 in the thickened portions 52 of the end walls 4, 5. Since the rotors 49 operate centrifugally the inlet slits 21a are dispensed with, and the interior surface `53 of rear and top walls 8, 2 facing the rotors 49 is formed as a scroll or volute, in conventional manner for centrifugal fans. The outlet duct 19 is formed between the top wall 2 and the bottom wall 3 and, once again, contains the heater unit 218. In operation air enters axially of the Irotors 49 through the inlets S1 and open ends 50, traverses the path of the rotating rotor blades 13 once generally radially into the outlet duct and thence flows past the heating element 28 to the outlet 18,

IIn other respects the hair dryer of FIGURES 4 to 5 is similar to that of FIGURIES 1 to 3: in particular a low voltage high speed commutator motor is once again used, connected in series with part of the element 28 so that the latter acts as a voltage dropper. This construction is illustrated in FIGURE 6 wherein the heater 28 is shown divided into two parts 100, 101 in parallel with one another. The low voltage motor 9 is connected such that the part 101 of the heater forms a voltage dropper for the motor to provide it with a small fraction only of the mains voltage. Switch 104 enables the part 160 which does not act as a voltage dropper for the motor to be switched on and off in order to regulate the amount of heat produced.

I claim:

1. A hair dryer comprising a casing having spaced end walls, top and bottom walls interconnecting the end walls, a curved rear wall merging into the top and bottomwalls of a size to iit between the thumb and forefinger when the casing is grasped in the hand, the end walls 'being formed with inlet openings and the casing defining a slot-like outlet opposite the rear lwall and extending over the width of the casing between the end walls, a commutator-type electric motor centrally located in the casing adjacent the rear end and having a shaft parallel thereto, a pair of cylindrical bladed r-otors overhung mounted on the 0pposite ends of the motor shaft and extending between Ithe motor and the respective side walls, an outet duct extending directly from the rotor to said outlet with the interior of said bottom wall of the casing forming a bottom side of said outlet duct, and electric heater means in the outlet duct; the rotors on rotation inducing flow into the inlet openings, through the rotor, through the outlet duct past the heater means and thence out of lthe outlet in the form of a flat jet.

2. A hair dryer as claimed invclaim 1, having in addition a partition wall extending in said casing between the end walls to define therewith and with the top wall an inlet region Iwhich communicates with the inlets, and guide wail surfaces positioned exterioriy of the rotor;

said guide wall surfaces and the interior of said rear wall on rotation of the rotors inducing flow of air twice through the path of the rotating blades of each rotor from the inlet region to said -outlet duct with said flow takingplace substantially in planes extending transverse to the axis of said rotors.

3. A hair dryer as claimed in claim 2, wherein the casing defines an additional inlet opening in a front part thereof above the outlet slot.

4. A hair dryer as claimed in claim 1, wherein the inlet openings are aligned with the ends of 4the rotors, and the rotors lare of the centrifugal type having open ends adjacent the end walls t-o receive air directly from the inlets.

5. A hair dryer as claimed in claim 1, wherein the motor and rotors form a sub-unit, and the casing is formed in two parts mating along a plane extending from the rear wall tow-ard the outlet, and one casing part receives and locates said sub-unit.

6. A hair dryer as claimed in claim 1, wherein the end walls converge towards the outlet to merge together the tiows from the two rotors.

7. A hair dryer as claimed in claim 1, wherein part of the electric heater means acts as a voltage dropper for the motor and the remainder of the heater means can be switched on and ofi.

8. A hair dryer comprising a casing having spaced end walls, top and bottom walls interconnecting the end walls, a curved rear wall merging into the top and bottom walls of a size to fit between the thumb and forelinger when the casing is grasped in the hand, inlet openings in said casing and the casing deiining an outlet opposite the rear wall, at least one bladed cylindrical rotor mounted :for rotation -adjacent said curved rear wall with its axis of rotation extending between Ithe end walls, a low voltage commutator type electric motor driving the rotor positioned adjacent the rear wall with its m-Otor shaft parallel to said rear wall, terminal means for connection to a m-ains voltage supply, and a first heater element positioned in the path of air flow between the inlet opening and the outlet opening with said first heater element being in permanent connection across said terminal means and in series connection with the motor Iwhereby said first element forms a voltage dropper lfor the motor to provide a. voltage therefore which is a ysmall fraction of the mains voltage.

9. A. hair dryer according to claim -8 having a second heating element positioned in the path of said air flow and means for switching said second heater element on and olf independent of the power supply `to `said first heating element and electric motor.

References Cited by the Examiner UNITED STATES PATENTS Eck 230--y ANTHONY BARTIS, Primary Examiner. 

1. A HAIR DRYER COMPRISING A CASING HAVING SPACED END WALLS, TOP AND BOTTOM WALLS INTERCONNECTING THE END WALLS, A CURVED REAR WALL MERGING INTO THE TOP AND BOTTOM WALLS OF A SIZE TO FIT BETWEEN THE THUMB AND FOREFINGER WHEN THE CASING IS GRAPSED IN THE HAND, THE END WALLS BEING FORMED WITH INLET OPENINGS AND THE CASING DEFINING A SLOT-LIKE OUTLET OPPOSITE THE REAR WALL AND EXTENDING OVER THE WIDTH OF THE CASING BETWEEN THE END WALLS, A COMMUTATOR-TYPE ELECTRIC MOTOR CENTRALLY LOCATED IN THE CASING ADJACENT THE REAR END AND HAVING A SHAFT PARALLEL THERETO, A PAIR OF CYLINDRICAL BLADED ROTORS OVERHUNG MOUNTED ON THE OPPOSITE ENDS OF THE MOTOR SHAFT AND EXTENDING BETWEEN THE MOTOR AND THE RESPECTIVE SIDE WALLS, AN OUTLET DUCT EXTENDING DIRECTLY FROM THE ROTOR TO SAID OUTLET WITH THE INTERIOR OF SAID BOTTOM WALL OF THE CASING FORMING A BOTTOM SIDE OF SAID OUTLET DUCT, AND ELECTRIC HEATER MEANS IN THE OUTLET DUCT; THE ROTORS ON ROTATION INDUCING FLOW INTO THE INLET OPENINGS, THROUGH THE ROTOR, THROUGH THE OUTLET DUCT PAST THE HEATER MEANS AND THENCE OUT OF THE OUTLET IN THE FORM OF A FLAT JET. 